Drill cutter



I Dec, 12, 1950 H. B. WOODS ETAL DRILL CUTTER 3 Sheets-Sheet 1 FiledJune 2, 1945 VENTORS BY Wax/ll) ATTORNEY Dec. 12, 1950 H. B. woons ETALDRILL CUTTER 3 Sheets-Sheet 2 Filed June 2, 1945 AUGKEEK Dec: 12 3.950

HEM/000s FLSCOTT INVENTORS BY flak fiq'flada.

31 10 ENE,

Patented Deco 12, 1950 DRILL CUTTER Henry B. Woods and Floyd L. Scott,Houston,

Tex., assignors to Hughes Tool Company, Houston, Tex., a corporation ofDelaware Application June 2, 1945, Serial No. 597,304

2 Claims.

Our invention relates to drill cutters for use in the drilling of wellsfor oil, gas and the like.

In the drilling of Wells, which sometimes are of great depths-such as,ten or fifteen thousand feetby the rotary method, there are used rotarydrills provided with cutters of general conical shape which arerotatably mounted. Such drills are fastened to the lower end of a hollowdrill stem which is rotated by suitable mechanism at the surface. Thecutters roll upon the bottom of the hole as the drillstem is revolved,and disintegrate the materials to be removed. Such roller cutters areprovided with teeth which are forced to penetrate the well bottom byweight of the drill stem, the same being controllable by the operators.

The disintegrated materials from the sides and the bottom of the holeare removed by a fluid which is pumped from the surface through thehollow drill stem, and are carried to the top and removed. The fluid notonly thus serves such purposes, but it also cleans and cools thecutters.

7 The form of the teeth and the arrangement of the same upon the conesare of great importance. It is desirable, as far as may be, to provideand arrange a cutting structure that will Work well in a plurality ofdifferent formations so as to minimize the necessity of withdrawing thedrill before it has exhausted its usefulness, in order to meet therequirements of varying formations.

Some of the very hard formations that must be drilledsuch as quartzite,hard sandy dolomite, or dolomite with chert or flint concretionsencountered in formations of the Paleozoic erahave high compressivestrength; also, in the main, they are very abrasive. To drill such hardabrasive formations requires the application of unusually heavy weightupon the drill to accomplish a satisfactory rate of penetration as wellas to secure a maximum footage per bit.

As the usual type of pyramidal teeth upon the cutters of the drillbecome worn, the area of contact of the dulled teeth on the formationincreases to such an extent as to require the application of increasingweight on the drill that may easily extend beyond the capacity ofpresent-day drilling equipment. In some instances, it has been foundthat as much as fifty thousand pounds Weight must be applied to a dull8%," diameter bit to secure practical drillin results. Since there areobvious limits to the strength of the parts of the drill, there is,therefore, a need for a cutting structure on the substantially conicalcutters which will permit of a satisfactory rate oi drilling with amedium weight such as 20,000#

to 30,000# supplied by suitable drill collars so that said cuttingstructure will continue to function well until it has been practicallyworn away in service. To this end, it is desirable to provide a cuttingstructure not easily broken and one that requires a minimum of weightupon the drill as the teeth of the cutters become dulled or shortened inoperation. To accomplish these results, we have provided in ourinvention a strong cutting structure such that as the cutting elementsare worn off, their area of contact on the well bottom will not greatlyincrease.

An object of the invention is to provide a circular, fiat-crestedcutting element for the coneshaped cutters, the crest area of which willnot rapidly increase as the cutting element wears, so that the bit willmaintain a desirable rate of penetration throughout the life of thecutters without necessity of unduly increasing applied weight.

Another object of the invention is to provide an outer row oflongitudinal teeth in combination with a plurality of inner,circumferential rows of flat-crested cutting elements, the said outerrow or rows to assist in the rotation of the cutters.

A third object is to provide a set of generally cone-shaped cuttershavin strong, segmental, flat-crested, circumferentially arrangedcutting elements spaced longitudinally of one of said cutters, the sumof the crest lengths of the segments in any row being less than the fullcircumference of said row, so that lower initial weight will be requiredto make said cutting elements penetrate the formation for more rap-idexcavation of the material to be drilled.

Another object of the invention is to provide a set of generallycone-shaped cutters having segmental, flat-crested, circumferentiallyextending cutting elements spaced longitudinally of said cutters, withsuch elements on adjacent rows staggered longitudinally, while thecutting elements on each of said cutters are staggered circumferentiallyso that as the cutters rotate, the Weight will not only be betterdistributed around each cutter as it rolls on the well bottom, but saidweight will be more evenly distributed between companion cutters of theset for better traction and prevention of intermittent overloading.

Another object is to provide a plurality of longitudinal cutter teethupon a cone cutter with a web joining one end of each tooth with theadjacent tooth on one side and with another web extending from theopposite end of the" same tooth to the next adjacent tooth on theopposite side to crush the ends of the rock teeth formed in the bottomof the hole by said longitudinal teeth. 7

Another object is to space widely the segmental, flat-crested,circumferentially extending cutting elements upon the cone to facilitatecleaning and acting together with adjacent cones, to cut the full wellbottom.

Other and further objectives of our invention will readily appear whenthe following description is considered in connection with theaccompanying drawings wherein:

Fig. 1 is a perspective view looking at the bottom of a well drillconstructed in accordance with the invention and illustrates theflat-crested segmental circumferential cutting elements.

Fig. 2 is a perspective bottom view of a slightly modified form of theflat-crested circumferential cutting elements where short segments arespaced circumferentially from each other.

Fig. 3 is a perspective bottom view of a slightly modified form of theflat-crested circumferential cutting elements where the elementconstitutes a continuous circle.

In Fig. 1 the bit bod 2 has the usual threaded shank 3 thereon by whichit is connected to the drill collar for rotation, and the conesupporting legs 4 upon which the cones 5 are rotatably mounted.

Three cones have been illustrated as being rotatable to perform thecutting action. These cones are usually designated as the No. 1 cone,which would be the cone '5; the cone 8 would be the No. 3 cone, whilethe cone 9 would be the No. 2 cone. These cones are usually so numberedbecause of the fact that the No. 1 cone has the most inwardly disposedor the smallest diameter cutting structure, the No. 2 cone has the nextlarger diameter cutting structure at its inner end, while the No. 3 conehas the third larger diameter cutting structure at its inner end. Sucharrangement is provided where the teeth are interfitting longitudinallyof the cone.

In describing the No. 1 cone, Fig. 1, which is the cone 1, the cone bodyis conical in shape and has an outer row of longitudinal teeth I Ispaced therearound. The outer ends ii of these teeth are joined by aconnecting web it. The purpose of the webs I3 is to trim down the rockteeth which tend to form at the junction of the bottom and wall of thehole. The cutting away of these rock teeth reduces wear on the outerends of the longitudinal teeth 92 and in this manner maintains the gaugeof the hole being drilled. One form of such web is shown in the priorpatent to Scott, No. 2,363,202, issued November 21, 1944.

Disposed inwardly of these longitudinal teeth are a plurality of rows ofcircumferential flatcrested cutting elements or projections. Theoutermost row !5 of such elements is made up of a single circumferentialelement 56, which is substantially less than an entire circle, and inthe drawing may constitute about one-third of a circle. The nextinwardly arranged element I! also comprises about one-third of a circleor less than half a circle, and is arranged. to begin at about where theelement i5 terminates. The third inner element is is similarly arrangedto begin at about the end of the cutting element 11 and to continue forabout one-third of a circle to terminate opposite the end of initialelement [5.

The arrangement of these elements may be described by stating that theyare staggered longitudinally of the cone 1 as well as being staggeredcircumferentially of the cone.

The particular structure of the ridge-like cutting element is such thatthe base portion 20 merges into the surface [9 of the cone and the body21 of the element projects substantially at right angles to the surfaceof the cone. The outside face 22 and the inside face 23 have beenillustrated as slightly tapering toward each other so that they arejoined by the crest 24. The sides are not necessarily so tapered,however. The crest 24 may be a flat crest and may have rounded cornersjoining the side faces.

For example, the width of the flat crest may approximate of an inch. Forhard rock such a cutting element has been found to be more efficientthan the pyramidal tooth structure disclosed in Patent No. 1,647,753, toScott, issued November 1, 1927, because of the greatly reduced area ofcutting surface allowed to contact the well bottom as the ridges weardown.

The No. 1 cone, 1, has the nose cutting structure 26, which may includethe annular notched circular cutter portion 2'. and the spear point 28so as to knock out any core or pedestal which would tend to form werethe spear point not there.

The No. 3 cone shown at 8 is similarly formed except that there is nospear point and the outer row of teeth H is slightly modified so thatthere is an inner web 3| joining the inner ends of two adjacentlongitudinal teeth I I. On the other end the opposite flanks of theteeth H are joined to the next adjacent teeth by the outer Webs I3. Thisarrangement leaves an internal pocket 35 between two adjacent teethwhile an external pocket 36 is arranged between the next two adjacentteeth.

The inside web 3| tends to reinforce the inner extremities of thelongitudinal teeth and crushes the ends of rock teeth that may begenerated on the well bottom. This cutting off of the ends of the rockteeth also assists the next inner row of cutting elements because therock teeth are destroyed in that region. This same action occurs at theperiphery of the hole due to the outer web [3 and in addition preventridges on the wall of the hole. The wide spacing of the circumferentialcutting elements and the interrupted areas tend to maintain the coneclean and prevent balling up.

The No. 2 cone, designated as 9 in the drawing, is formed with thecircumferential elements I 6, I! and [8, as heretofore described, buthas a slightly modified arrangement of the longitudinal teeth II, inthat they are somewhat longer than the teeth II of the cone 1. Eachtooth l l on cone 9 is provided with a recessed area 40 to allowclearance for the inner ends of teeth II on cone 8. The inner webs 3|and the outer webs I2 are the same as previously described in connectionwith the cone 8. The slight extension 45 of the webs l2 on the outerends of the teeth ll may be provided so as to form a relatively narrowslot 46 as defining the outer pocket 36. Thi structure is of advantagebecause it makes an overlapping track on the bottom of the hole aroundthe periphery so as to prevent the formation of rock teeth. Theseextensions provide additional area for deposition of tungsten carbide tohelp maintain the gauge of the hole.

It should be borne in mind that all the rock encountered is not of thesame hardness; that the rock is stratified in harder and softer areas sothat in some instances, due to the weight on the bit, the cones may havea tendency to slide on bottom rather than to roll. The longitudinalteeth I I provide traction to discourage such sliding, particularly whena softer rock formation is encountered.

Broadly the invention contemplates an arrangement of relatively narrowcircumferential flat-crested segmental ridge-like cuttin elements on therotating cone; the combination therewith of the circumferentially webbedcutters for the outer row; and also the combination of the inside andoutside alternate webbed portions.

Fig. 2 shows a slightly modified form of the construction where theouter rows of teeth on the cones l, 8 and 9 are the same as previouslydescribed, but the circumferential segmental ridges l5, 16, I1, and E8of Fig. 1' have been modified so that they form the circular rows 50, 5|and 52. These circular rows are each made up of a plurality of shortsegments or projections 53, which are similar to the segmental teeth l5of Fig. 1, except that the segments are much shorter and spaced apart bythe openings 54. Of course, the rows on the No. 1, No. 2, and No. 3cones are offset relative to each other so as to permit interfitting.

Fig. 3 shows another slightly modified form of the arrangement whereinthe outer teeth are the same as previously described but thecircumferential ridges l5, l6, l1 and 18 of Fig. 1 are in the form ofcomplete circles 6|, 62, 63, as best seen on the No. 1 cone of Fig. 3.These ridges on the several cones are also interfitting. Sucharrangement permits cleaning of adjacent cones, and allows greaterheight of the cutting elements which in turn renders a greater cuttinglife. An advantage of the circumferential cutting elements resides inthe fact that the elements do not appreciably increase in crest area asthey wear down and consequently cut at a rate approaching their rate ofcutting when new.

Broadly the invention contemplates a combination of cutter teeth forrotary cone well drilling wherein longitudinal and circumferential teethare provided, where such teeth may be 6 complete circles, or differentlength segments thereof.

What is claimed is:

1. A cone type well drill including a head having mounted thereon aplurality of cones to roll upon and disintegrate the well bottom, aplurality of completely circular independent cut ting elements havingcontinuous annular crests spaced longitudinally of at least one of thecones, each cutting element including a body portion projecting atsubstantially right angles from the cone surface and having slightlytapered side surfaces joined at their outer ends by the continuousannular crest.

2. A cone type well drill including a head, three roller cones mountedthereon to roll upon and disintegrate the well bottom, a plurality ofcompletely circular independent cutting elements having continuousannular crests and spaced longitudinally of at least one of the cones,each cutting element including a bottom portion projecting from thecone, the circular cutting elements of each cone being offset withrespect to the cutting elements of the adjacent cones and spaced alongthe surface so that each cutting element inter-fits between cuttinelements of each adjacent cone and together the cutting elements on thecones cut the entire bottom of the well.

HENRY B. WOODS. FLOYD'L. SCOTT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,896,251 Scott Feb. 7, 19331,918,902 Fletcher et al July 18, 1933 2,027,700 Rogatz Jan, 14, 19362,151,348 Fisher Mar. 21, 1939 2,176,358 Pearce Oct. 1'7, 1939 2,177,332Reed Oct. 24, 1939 2,228,286 Ross Jan. 14, 1941 2,294,544 Garfield Sept.1, 1942 2,333,746 Scott et a1 Nov. 9, 1943 2,363,202 Scott Nov. 21, 1944

